Siegmund Posted September 15, 2010 Posted September 15, 2010 Is the color of a zinc star enhanced by the presence of a chlorine donor or not? We don't add chlorine to get brighter whites from titanium or brighter yellows from iron; one of the pluses of magnalium-fueled colored stars is that the MgCl doesn't interfere with the color from SrCl or BaCl... but I haven't seen much in the literature, good or bad, about zinc... for that matter, other than variations on the granite star, I haven't seen many zinc compositions at all. If nobody has any insights, I may experiment some myself -- out of necessity, as it's the time of year that water-based stars just won't dry outdoors anymore but acetone still evaporates -- but there's a choice to be made whether to bind them with parlon or with red gum.
WSM Posted January 2, 2011 Posted January 2, 2011 (edited) Is the color of a zinc star enhanced by the presence of a chlorine donor or not? We don't add chlorine to get brighter whites from titanium or brighter yellows from iron; one of the pluses of magnalium-fueled colored stars is that the MgCl doesn't interfere with the color from SrCl or BaCl... but I haven't seen much in the literature, good or bad, about zinc... for that matter, other than variations on the granite star, I haven't seen many zinc compositions at all. If nobody has any insights, I may experiment some myself -- out of necessity, as it's the time of year that water-based stars just won't dry outdoors anymore but acetone still evaporates -- but there's a choice to be made whether to bind them with parlon or with red gum. Where ordinary color stars require a chlorine donor to achieve a monochloride species at high temperature to get a saturated color. zinc is an elemental colorant (it doesn't require anything else to give the blue-green color we're familiar with). Zinc is touchy stuff, too; often requiring the addition of potassium dichromate to passivate it in mixtures that are water bound (electric spreaders come to mind). Zinc is very reactive and needs to be protected, somewhat similar to magnesium. Both of these metals are used for cathodic protection as sacrificial anodes. I have no idea how zinc would react to chlorine donors. If experimenting with unknowns, it is wise to work in as small a quantity as possible and test for as many variables as you can (ignition, impact, friction, chemical compatibility, storage at various temperatures and humidities, et cetera) before you let yourself get comfortable with it. It may be a tiger, waiting to get you. Do be careful. WSM Edited January 2, 2011 by WSM
Siegmund Posted January 5, 2011 Author Posted January 5, 2011 Reactivity in water-bound mixtures seemed to me like it was a case in favor of using an organic binder on my zinc stars. I wound up making a 100g batch of essentially the standard granite recipe plus parlon, either 7 or 10%, I'd have to recheck my notes, and was happy with the result. I didn't notice a difference in the color as compared to zinc-without-parlon (but I didn't make a batch with red gum or with dextrin and water and fire them side by side, either.) There is an ancient thread on the UK pyro society forum claiming that Zn+nitrate stars were more bluish while Zn+perchlorate were more green. It's the closest thing to a reference to the effect of Cl on Zn that I've ever found. I've never tried a Zn+perchlorate star myself. Damn, its a long winter!
Voryon Posted January 5, 2011 Posted January 5, 2011 I`ve been fooling around with chlorate/sugar/zinc mixes (<- not recommended) when I was young. From what I can remember, the addition of hexamine enlarged the greenish-blue flame envelope significant. Thats not the answer to the parlon question but could be giving direction to an enhanced granite star.
Mumbles Posted January 5, 2011 Posted January 5, 2011 Unless special measures are taken, perchlorate typically doesn't give up it's chlorine very regularly. The difference in color could have been as simple as different flame temperatures. Zinc and aluminum are somewhat related and similar in their properties. Aluminum chloride is relatively invisible in the visible range, so it would not surprise me if zinc chloride was as well. That's purely speculation of course.
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